This is a place to find out about commercial and non-commercial uses of Squeak.

(A review of the validity of some of the content found here would be nice, though.)

(A more specific list of commercial-only projects can be found at List of Commercial Projects using Squeak.)
A company called Exobox used Squeak to implement an extremely easy to use, Internet-savvy, user environment for deployment on Internet appliances. See Exobox for more info and some impressive screenshots.
Squeak web servers:

The Swiki you are reading is a Squeak server

...

Much of what I know about Squeak, I learned by building Questa's Soil Classification application, which displays soil sample data as a ternary plot, and classifies each sample by its USDA standard soil texture.

Lawrence Press
Questa Engineering Corp.
I'm using Squeak to write an autonomous controller for a robotic submersible. You can check out some screenshots of the autonomous controller running in a simulator (also written in Squeak) at:

I was originally planning to port the autonomous controller (AC) to Pocket Smalltalk, since Squeak doesn't really fit on a Palm device, but I found a new PDA, the VTech Helio, that runs Squeak nicely. The AC code is basically Smalltalk-independent, while the simulator is definitely Squeak-only, using Morphic for all the graphics stuff, and the animation in Morphic to both animate the GUI and to also step the AC.

The IDE for Pocket Smalltalk, Smalltalk for small devices, currently running on Palm OS and GEOS has been ported to Squeak.http://www.PocketSmalltalk.com
The IDE is currently in alpha and has some problems. We are actively working on moving this to beta and release. The new version will include a source level debugger that will run in Squeak on a main computer, with the Pocket Smalltalk code running on the device itself.
Some other miscellaneous commercial projects involving Squeak: (copied from the GaTech cs2340 FAQ page... some of these may be out of date, such as the Interval project)

Disney is developing video games in Squeak (see Disney Blast and the 20,000 Leagues under the Sea videogame at Disneyland)

Stono Technologies (Chicago) is building a new stadium broadcast system in Squeak.

Others (IBM, Interval Research) are using it in-house for prototyping and development

TFEI (The Fourth Estate Inc.) in San Diego

Phaidros Software AG in Germany

Tomandandy in NYC is building an algorithmic music system in Squeak

A question for the community: Has anyone actually distributed Squeak applications? Been paid hard currency for a product produced with Squeak on any platform? Many Squeak users could really benefit from any experience you have to share.http://www.minidata.ca/

We develop scheduling applications. Our Production Scheduling software with interface to MRP is written in Squeak and we are converting distribution center scheduling software from VisualWorks 3.0 to Squeak.

Link Graveyard (sites that no longer exist or no longer appear to be squeak related)

SqueakNews uses Squeak to create an interactive e-zine sold by CD-ROM subscription. The SqueakNews e-zine is also about Squeak, of course, but the company is also working on creating CD-ROM e-zines on other topics such as cooking and Kung Fu/self-defense, using the same Squeak-based technology.

http://www.cosmocows.com No longer exists as described (Dec 2011). CosmoCows develops the InternetInvolver; for everyone who wants to visit, use, tweak or create new media. The InternetInvolver provides the technological infrastructure to transport, present and manipulate all kind of multimedia objects over the internet. This will give its users a better tool to express, amplify, place and share their thoughts in the virtual world.

The company Vibrant3D is using Squeak as a scripting/development platform for its V3 graphics engine. http://www.vibrant3d.com/ No longer exists as described (Dec 2011).